Apparatus for producing panty hose

ABSTRACT

A sewing machine particularly constructed for the manufacture of panty-hose or tights by simultaneously sewing two parallel seams in two stockings, from a point part-way down from the open end thereof which will form, in the finished garment, the crutch portion of the tights, towards the open end, and slitting between the two seams to complete the tights. The machine is particularly characterised in that it has two pairs of needles each pair forming a seam having a double row of stitches joined by a covering thread and a filler cord and one row of which lies substantially on the edge of a slit in the fabric previously formed by a cutter blade of the machine. The machine operates to sew the two seams in such a way that they interlock at the crutch portion of the garment to prevent the formation of runs starting from this point.

United States Patent [191 Cassinelli Nov. 4, 1975 [5 APPARATUS FOR PRODUCING PANTY HOSE [75] Inventor: Giuseppe Cassinelli, Varese, Italy [73] Assignee: Calze Malerba S.p.A., Varese, Italy [22] Filed: July 18, 1974 [21] Appl. No.: 489,662

[30] Foreign Application Priority Data Primary ExaminerH. Hampton Hunter Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak ABSTRACT A sewing machine particularly constructed for the manufacture of panty-hose or tights by simultaneously sewing two parallel seams in two stockings, from a point part-way down from the open end thereof which will form, in the finished garment, the crutch portion of the tights, towards the open end, and slitting between the two seams to complete the tights. The machine is particularly characterised in that it has two pairs of needles each pair forming a seam having a double row of stitches joined by a covering thread and a filler cord and one row of which lies substantially on the edge of a slit in the fabric previously formed by a cutter blade of themachine. The machine operates to sew the two seams in such a way that they interlock at the crutch portion of the garment to prevent the formation of runs starting from this point.

5 Claims, 20 Drawing Figures Sheet 1 of 11 U.S. Patent Nov. 4, 1975 U.S. Patent Nov. 4, 1975 Sheet20f1i 3,916,808

U.S. Patent Nov.4, 1975 Sheet3of11 3,916,808

U.S. Patent Nov. 4, 1975 Sheet4ofll 3,916,808

U.S. Patent Nov. 4, 1975 Sheet50f11 3,916,808

m OH E d L dmm w n l n r U.S. Patent Nov. 4, 1975 Sheet6of11 3,916,808

Fig-11 Sheet 7 0f 11 US. Patent Nov. 4, 1975 Patent NOV.4, 1975 Sheet8of11 3 916 808 nl llll S US. Patent Nov.4, 1975 Sheet 10 ofll 3,916,808

m w W f. in ww Tfi ZN U.S. Patent -N0v.4, 1975 Sheet 11 0111 APPARATUS FOR PRODUCING PANTY HOSE BACKGROUND OF THE INVENTION The present invention relatesto apparatus for producing panty hose and particularly to a sewing machine for sewing together two fabric tubes for producing panty hose of the type commonly known as tights and consisting of two tubular stockings joined at the top (that is the open end) at hip level.

One method of manufacturing tights is to first knit two tubular stockings and then to join these longitudinally with two rows of stitching extending a certain distance from the open end of each, a slit is then made between the two rows of stitching to complete the finished product. Alternatively the tights can be made by first making a slit in the areas to be joined and then effecting sewing (or welding, if the material of the fibres is suitable) along the cut edges. Alternatively one seam may be made and the slit formed simultaneously. Known apparatus for performing this operation comprises two arms, placed one above the other a short distance apart, extending cantilever fashion from a fixed support structure, and defining between them a space, into which the fabric tubes to be sewn are inserted in operation of the machine. The two arms carry means for sewing a scam in fabric placed between the arms, and a cutter element for making a longitudinal slit in a fabric, adjacent the seam being sewn.

With this type of sewing machine, after having brought together the two tubular stockings to be joined, a first pass is made starting from the area which, in the finished garment, will form the waist, down to the crutch portion; the machine simultaneously effects cutting of the fabric and sewing along one edge of the cut. Next, the operator has to rotate the fabrics so as to reposition them in order to carry out a second pass from the crutch to the waist, during which the remaining two out edges are sewn together. It will be apparent that this procedure demands particular care on the part of the operator, especially in effecting rotation of the fabrics and in keeping the cut edges of the fabric to be sewn close together after the first pass has been effected, so as to produce a neat seam with the second pass.

In order to facilitate this operation it has been proposed (in US. Pat. No. 3,711,866) to draw the two stockings to be joined together to make tights, onto two suitably shaped forms which are then placed together and the portions of fabric which are to be sewn together are drawn together and sewn with two parallel seams extending side-by-side from what will be the crutch portion of the finished garment to the open end of the stockings (which will form the waist). The fabric between the two seams is then cut, preferably while the two stockings are still on the forms. The apparatus used for effecting such a procedure comprises a sewing machine of known type having two needles operating at the same time, and a cutting member for cutting betweenthe two seams made by the said two needles.

One disadvantage of this method is that the two seams remain spaced from each other at the ends which will form the crutch portion of the finished garment. In addition, the two parallel seams run very close to the cut edges and the stitching of these seams does not lock the threads of the raw, cut edge, of the fabric. Thus, particularly in the region .of the crutch portion at the end of the cut between the seams. there is nothing to stop the formation of runs along the length of the said cut, during use of the finished tights. Moreover, the cut edges of the fabric along the two seams are left raw, and since the seams are at a very small distance from the edges formed by the cut there is a distinct tendency for the edges to unravel thus promoting the forming of further runs. Unravellin g also causes a tendency for the seams to come undone. The technical problem of this invention is to provide apparatus for providing tights of the above mentioned type, of an improved quality, particularly in the region of the crutch, reducing to a minimum the likelihood of runs, slacks or unravelling adjacent the seams, whilst at the same time ensuring very quick and simple manufacture.

SUMMARY OF THE INVENTION According, therefore, to the present invention there is provided a machine for sewing together two fabric tubes for producing pany hose of the type commonly known as tights, and consisting of two tubular stockings connected together in the region of the open ends thereof, the machine comprising two substantially horizontal parallel arms one above the other extending from a fixed support structure and carrying means for sewing two seams in fabrics placed between the arms, and for slitting the fabric longitudinally of and between the two seams, characterised in that one of the said two arms carries two pairs of needles mounted for reciprocating movement towards and away from the other arm, one needle of each of the said two pairs of needles being positioned in approximate alignment, in the direction of the seams, with the means for slitting the fabric between the two seams, two pairs of hooks, one pair carried on one arm and the other pair carried on the other arm, means for feeding threads to the said pair of needles and the said pairs of hooks, and means for imparting synchronised movements to the said needles and the said hooks whereby to form in a single operation two double rows of stitching and to slit the fabric tubes between the two double rows of stitching, to form a pair of tights from the said two fabric tubes.

One advantage of the sewing machine of this invention is that it operates to join the fabrics, along each of the two edges made by the cut, by a double row of stitching which runs parallel to and adjacent the cut edge of the fabric; the double rows of stitching are preferably of a stitch which locks the threads of the cut edge of the fabric to provide an excellent finish to the seams of the tights. Another advantage of the invention rests on the fact that, the sewing precedes the cutting because the aligned arrangement of the needles and of the cutting member means that these must be displaced axially of the seam so that an initial section of seam is made in which the two double rows of stitching intersect, effectively locking the fabric threads at the crutch portion and thus preventing the formation of runs along the length of the cut.

BRIEF DESCRIPTION'OF THE DRAWINGS A preferred embodiment of the invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic perspective view of a sewing machine according to the invention;

FIG. 2 is a cutaway perspective view, on an enlarged scale, of a part of the sewing machine of FIG. 1, showinga part of the mechanism for operating the needles;

FIGS. 3, 4 and 5 are perspective views illustrating three successive stages in the production of a pair of tights;

FIGS. 6, 7 and 8 are diagrams illustrating the formation of the seams of a pair of tights using the sewing machine of FIG. 1',

FIG. 9 is a perspective view on a larger scale illustrating the stiches which are formed by the sewing machine described herein;

FIG. 10 is a perspective view on a larger scale schematically illustrating the formation by the sewing machine described herein of the stitches at the crutch portion of a pair of tights;

FIG. 11 is a perspective view, on a further enlarged scale, of a detail of the stitches shown in FIG. 10;

FIG. 12 diagrammatically illustrates the formation of the stitches by the sewing machine described herein;

FIGS. 13, 14 and 15 are exploded perspective views of some of the elements of the mechanism shown in FIG. 2;

FIGS. 16 and 17 are respectively vertical and horizontal partial sectional views of the upper arm of the sewing machine showing the mechanism for transmitting movement to the needles of the machine to cooperating hooks;

FIG. 18 is a cross section taken along the line XVIII- XVIII of FIG. 16;

FIG. 19 is a plan view of a workpiece support plate of the sewing machine described herein; and

FIG. 20 is a diagrammatic perspective view of a pair of tights which can be made with the sewing machine of the invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Referring now to the drawings, and in particular to FIGS. 1, 2, l3, l4 and 15, the sewing machine of the invention comprises a support structure 1 from which project two parallel cantilever arms 2 and 3 which, in the normal operating position of the machine, are hori' zontal, and one above the other. The arms 2, 3 are of a length slightly greater than the length of the seams which are to be made by the machine, and they are positioned relatively close to each other so as to delimit a space 4 between them to receive the pieces of fabric to be joined together. The said arms 2 and 3 have a hollow box section and each houses an appropriate part of the sewing mechanism.

Adjacent the free end of the upper arm 2 there are carried two pairs of needles 9 and 9a fixed by means of screws 8a, to a block 8b having a stem 8c (FIG. 13). The block 8b is fixed to another block 8 by inserting and locking the said stem 80 into a hole 8d in the block 8. The block 8 also has a through hole 82 (FIG. 13) through which passes a fixed vertical shaft 8 along which the block 8 is slidable. The bar 8f is fixed to the upper wall of the structure of the arm 2 and is free at the bottom, and serves as a guide for the up and down sliding movement of the block 8. To the upper side of the block 8 there is fixed a thread guide 10 having bores through which there pass the threads feeding needles 9 and 9a of the machine. I

Close to these needles 9 and 9a and in a central position (as will be seen later) there is fixed a cutter in the form of a sharp blade 11 which has a stem which is locked, by means of a screw 11a (FIG. 13) on to a sinker llb which is fixed to a part of the block 8 by means of screws 110. The sinker 11b is provided with a bore 1 1d corresponding to the through-hole 8e, through which passes the guide bar 8 f. The block 8 is also fitted with a lug 8g which is attached by a pivot 7a to one end of a double link rod 7 the other end of which is connected, by another pivot 7b, to one arm of a rocker 5. The rocker 5 is pivotally mounted on a horizontal pivot 5a extending transversely across within the framework of the upper arm 2, and the arm thereof opposite that which is connected to the double link rod 7 has a bifurcated end 512 in the form of a fork carrying a pin 6a to which is attached one end 6b of a rod 6 (FIGS. 2, 16, 17).

The other end 60 of the rod 6 is connected to a crankshaft 6d (FIGS. 16 and 17) the axis of which extends horizontally within the fixed structure 1 and which is driven in a known manner by a motor (not illustrated) of the machine.

In cooperation with the needles 9 and 9a there operate two hooks 12 and 12a which move angularly around a vertical axis. The hooks l2 and 12a are located in respective holes 12b in a block 120 and held in place in the block by screws 12d (FIG. 15). The block 120 is provided at the centre with a through-hole 12e into which is inserted a bush 12f having a radial flange 12g at the lower end thereof. The block 12c can move angularly around the bush 12f the upper end of which extends above the upper surface of the block 12c and is inserted into a bore 13a in a clamping block 13, into which the said bush 12f is clamped. The clamping block 13 is provided laterally with a lug 13b extending at to the general plane of the block 13, for fixing the block 13 to the inner lateral wall of the upper arm 2.

In operation of the machine an angular reciprocating movement around the bush 12f is imparted to the block and this is achieved by means of a rod 14 (FIGS. 15 and 17), which is carried within the upper arm 2 and which has one end 14a connected to a crank of the crankshaft 6d and the other end provided with a connecting element 14b having a spherical socket housing a ball end which is attached to the block 120 (FIGS. 15, 17 and 19), to form a swivelling ball joint.

Near to the hooks l2 and 12a there are placed respective reciprocable thread guides 15 and 15a. The thread guides 15 and 15a are fixed to a rod 15b which, in its turn, is attached to an eccentric pin 150, through a connecting element 15d (FIG. 15). The rod 15b is a sliding fit in a vertical bore 15e extending through a projection 15f of a sinker 15g having two holes 1511 through which pass two locking screws 15i which hold the sinker 15g to the clamping block 13.

The pin 15c is connected to one end of a link rod 15] the other end of which is joined, by a screw 15m, to a lug 15n of the block 12c (FIGS. 2 and 15).

Thus, angular reciprocation of the block 12c caused by the rod 14, induces a corresponding reciprocation of the thread-guides 15 and 15a carried by the rod 15b. The link rod 15l transmits the angular reciprocating movement to the block 12c to the pin which thus reciprocates angularly around the axis of the rod 15b to which there is therefore imparted a corresponding angular reciprocation around its own axis.

The angular movement of the thread-guides 15 and 15a ensures feeding to the hooks l2 and 12a of their respective threads. Below the hooks l2 and 12a there is assembled, according to a known arrangement, the

so-called foot 18 of the machine which assists in moving the fabrics being sewn across the sewing area. The foot 18 is fixed, by means of a block 18a (FIG. 14) to a vertical bar 19 which passes through and is slidable in the bushing 12f, and which supports at the top a transverse element 20 having an opening 20a in which the bar 19 is clamped. The element 20 extends laterally of the bar 19 and into a guide slot b in one side wall of the arm 2 (FIGS. 2 and 18).

, In the lower arm 3 there are assembled two lower hooks l6 and 16a arranged in positions corresponding to those of the upper hooks 12 and 12a of the upper arm 2. The lower hooks 16 and 16a are fixed, by means of screws 16b, axially spaced from one another upon a single shaft 17 which extends horizontally and longitudinally of the lower arm 3 and which, by means of a suitable linkage (not shown, as it is of known type) is given a reciprocating movement by the motor (not shown) of the machine.

The hooks 16 and 16a are also fed with respective threads in a known manner. As will be described more fully below, the upper hook l2 and the lower hook l6 cooperate with the pair of needles 9, whilst the upper hook 12a and the lower hook 16a cooperate with the other pair of needles 9a. The upper face 21 of the lower arm 3 is closed at the free end by a horizontal rectangular upper plate 21a (FIG. 19). This plate 21a is fixed by means of screws 21b and has longitudinal slots 21c which allow the teeth projecting from a feed element 22, commonly known as a jaw to extend therethrough. In a known manner this jaw is fixed to a bar 23 (FIG. 2), operated by a known type of mechanism (and therefore not shown) so as to impart a suitable combination of reciprocating movements in the vertical and horizontal directions in order to cause feed movement of the fabric being sewn across the sewing region in a direction parallel to the length of the arms 2 and 3 away from the support structure 1 and towards the free ends of the arms 2 and 3, that is along the plate 21a from an end 21] thereof towards an end 2li thereof.

The plate 21a (FIG. 19) is moreover provided in a central position, between the slots 21c, with a notched opening 21d which includes two notches 212 for passage of the needles 9 and two notches 21f for passage of the needles 9a. One of the two notches 211, and one of the two notches 21f is joined to the main opening 21d by a respective elongate L-shape slot. The notches 2le and 21f of each pair are positioned laterally side by side, and the two pairs are axially displaced a small distance. The notches of each pair 2le and 21f nearest the other pair are positioned approximately on a centre line 21g of the arm 3, as shown in FIG. 19. Also on the centre line 21g there is a slot 21h through which, in use of the machine, extends the end of the cutter blade 11.

The end 2li of the plate 21a is positioned towards the free end of the arm 3 and the other end 211 is positioned towards the support structure 1 for the arm 3; the notches 21c, 21 f and the slot 21h shown in FIG. 19, exactly define the positions of the needles 9, 9a and the position of the cutter blade 11. This latter therefore is fixed immediately upstream of the needles 9, 9a (with respect to fabric movement during sewing), between these and the support structure 1' for the arms 2 and 3.

The position of the needles 9, 9a and of the blade 1 1 is also clearly shown in FIGS. 6, 7 and 8. The needles 9 and 90i a extend across the space 4 between the arms and are perpendicular to the upper face 21 of the lower arm 3.

To facilitate the positioning of the stockings to be joined by the machine described two forms 24 are used (FIG. 3); these each have one open side and are shaped to be fitted into the open end of the tubular stockings 25 and 26 (FIG. 4) which are to be joined. The forms 24 extend only into the upper sections of the stocking 25 and 26, when the sewing is to take place, and allow the stocking tops to' be stretched to define the portions 25a and 26a which are to be sewn and cut.

After assembly upon the forms 24 the said portions 25a and 26a of the fabric tubes are brought face to face by sliding the said forms 24 over the arms 2 and 3 (FIG. 5) and moving them along until they approach the zone where the arms 2 and 3 are attached to the support structure 1 (FIG. 6). When the forms, and the stockings are in position the sewing machine is operated to make, in a single operation, a pair of tights from the two stockings 25 and 26 by forming simutaneously two rows of double stitching the stitches of which are linked, as shown in FIGS. 9, 10, 11 and 12, by a transverse covering thread 29 below the fabric, and a filler cord 28 above the fabric, the covering thread 29 being fed by the hooks 16,1611 and the tiller cord 28 being fed by the hooks l2, 12a. In FIG. 1 there can be seen, at 27b the bobbins carrying the threads 27 which feed the two pairs of needles 9 and 9a.

From the above description, the operation of the sewing machine will be apparent to one skilled in this art; the movement of the various needles and hooks are coordinated by means well known in this art and thus will not be described in greater detail.

Rotation of the crankshaft 6d induces, via the rod 6, vertical reciprocating movement of the block 8 along the guide bar 8f causing a similar reciprocating movement of the needles 9, 9a and of the blade 11. At the same time the rod 14 causes reciprocation of the block and hence a corresponding angular reciprocating movement of the hooks 12 and 12a. Synchronising with this the hooks l6 and 16a, fixed to the shaft 17, will also reciprocate angularly.

FIG. 10 shows, on a greatly enlarged scale, the stitches made along the cut edge portions 25a and 26a of fabric, using the machine described above, and FIG. 9 shows the formation of the stitches with the two rows shown spaced apart'from each other, to make the drawing clear. The fabric being sewn has also been shown folded in FIG. 9, in order to show the form of the stitches on both sides of the fabric. As will be seen from FIG. 9 the lower hooks l6 and 16a move together with a substantially elliptical movement, as indicated by the dot and dash lines 30, in the direction of the arrows A, and cooperate with the needles 9 and 9a, to make the through-going loops 26a and to link these with loops of the covering thread 29 which is fed by hooks l6 and 16a and which lies only on the lower face of the fabric. In effect the needles 9 and 9a, together with the hooks l6 and 16a below make four parallel rows of stitches, the rows being linked together in pairs by the covering threads 29 which lie on the lower face of the fabric. The stitches made by the threads 27a and 29 as seen in FIG. 9, and the method of forming these with the ma chine described will be apparent to those skilled in the art. The particular stitch used is similar, in some respects, to a buttonholing stitch.

At the same time the upper hooks 12 ans 12a, feed the thread serving as filler cord 28 and, moving together in the same way as the hooks 16 and 16a, link the thread 28 with the loops of the thread 27 on the upper side of the fabric; the filler cord 28, however, does not form part of the stitch but merely extends in a meandering fashion between the associated two rows of stitches forming flat, open, loops which serve to finish off the upper side of the edge portions 25a and 26a of the fabric, as seen in FIGS. 9 and 10. Synchronising with the movement of the hooks, the needles 9 and 9a reciprocate, together with the blade 11, perpendicularly to the fabric between the arms 2, 3 so that each pair of needles 9 and 9a forms a double row 31, 31a of stitches connected transversely by the covering thread 29 and the filler cord 28. Each double row 31 and 31a of stitches is sewn along a respective raw edge of the fabric so that the actual positions of the stitches with respect to the edge of the fabric is not that shown in F109 but is more as illustrated in FIG. which shows one row of stitches in each double row being sewn effectively on the edges of the cut 32 so as to finish these off and to resist fraying or unravelling of the threads of the fabric.

Referring now to FIGS. 6, 7 and 8, in order to illustrate the operating sequence during use of the machine described: after the portions 25a and 26a of the fabric tubes or stockings to be joined have been inserted between the arms 2 and 3, the machine is started and the first few stitches are formed as shown in FIG. 6, with the needles 9 and 9a at the level of what will be the crutch of the finished tights. The blade 11 also begins to move backwards and forwards vertically in synchronism with the needles 9, 9a, but since the blade 11 is positioned upstream of the needles 9 and 9a, the cut part of the fabric does not reach the needles until they have completed several stitches at an uncut part of the fabric in which, as shown in FIG. 10 the two double rows are interlinked. This interlinking of the two double rows of stitches is important since it is this that prevents the formation of runs in the crutch part of the finished garment.

As soon as the sewing machine is started the jaw 22 commences feeding the fabrics in the direction of the arrow B of FIGS. 6, 7 and 8, that is in a sense such that the seams are sewn from the crutch portion at which sewing commences, towards the open ends of the fabric tubes, which will form the waist of the finished garment. While sewing is taking place the blade 11 is making a cut in advance of the needles and at a position between the two double rows of stitches. As the slit cut by the blade 11 reaches the needles 9, 9a the two double rows 31, 31a of stitches continue, one along each cut edge of the slit.

As best seen in FIG. 12 the two pairs of needles are offset from each other in the direction of feed with a first needle of each pair being disposed in longtitudinal alignment with the blade 11. Plus during the initial stitching operation several stitches formed by the needle 9 which is in alignment with the blade 1 1 will be super-imposed upon the stitches formed by the needle 9a which is in alignment with the blade. This is best seen in FIG. 10 which clearly shows the super-imposed stitches which are interconnected by means of the filler thread 28. As the slit portion of the fabric reaches the needles the two needles which are aligned with the blade will penetrate along the slit line so that two double rows of stitches are formed with one row of each double row being disposed at the very edge of the cut fabric.

The machine completes the seams formed by the two double rows 31, 31a of stitches by running off the open ends of the fabric tubes as shown in FIG. 8.

Thus in a single operation, the two fabric tubes are cut and sewn together, the cut edges are finishedoff to prevent fraying and unravelling and the crutch portion of the finished garment is reinforced by interlocking the two seams at this point thereby avoiding the formation of runs starting from this point.

As will be appreciated, with the sewing machine of the present invention the operation of joining and slitting two tubular stockings so as to form a pair of tights of high quality can be effected rapidly and simply, and can be carried out even by unskilled machine operators.

I claim:

1. In a machine for sewing together two fabric tubes for producing panty hose of the type commonly known as tights, and consisting of two tubular stockings connected together in the region of the open ends thereof, said machine comprising:

a fixed support structure;

first and second substantially horizontal parallel arms one above the other extending from said fixed support structure; means on said first and second arms for sewing two seams in fabrics placed between said arms, and means for slitting the fabric longitudinally of and between said two seams, being positioned ahead of said sewing needles with respect to the direction of movement of the fabric the improvement comprising said means for sewing two seams including two pairs of needles mounted on said first arm for reciprocating movement towards and away from said second'arm, one pair of needles being offset from the other in the direction of said seams with a first needle of each of said two pairs of needles being positioned in approximate alignment, in the direction of said seams, with said means for slitting the fabric between said two seams so that said first needle of each pair will enter the slit in the fabric, two pairs of hooks, a first pair being carried on said first arm and a second pair being carried on said second arm, means for feeding threads to said two pairs of needles and said two pairs of hooks and means for imparting synchronised sewing movements to said needles and said hooks whereby to form in a single operation two double rows of stitches and to slit the fabric tubes between the two double rows of stitches to form a pair of tights from said two fabric tubes. 2. The sewing machine of claim 1, wherein said arms are of a length at least equal to the length of a seam from the crutch portion to the waist of a pair of tights.

3. The sewing machine of claim 1, wherein said first arm is the upper arm and it carries said means for slitting the fabric being sewn, said two pairs of needles and an upper pair of said two pairs of hooks and said second arm is the lower arm and it carries a lower pair of said two pairs of hooks.

4. The sewing machine of claim 3, wherein each pair of said two pairs of needles operates in combination with an associated lower hook to form a double row of stitches comprising two threads which pass through the 10 of said needles also cooperates with an associated one of said upper hooks to interlace the loops of said two threads which pass through said fabric with a filling cord on the upper side of said fabric. 

1. In a machine for sewing together two fabric tubes for producing panty hose of the type commonly known as tights, and consisting of two tubular stockings connected together in the region of the open ends thereof, said machine comprising: a fixed support structure; first and second substantially horizontal parallel arms one above the other extending from said fixed support structure; means on said first and second arms for sewing two seams in fabrics placed between said arms, and means for slitting the fabric longitudinally of and between said two seams, being positioned ahead of said sewing needles with respect to the direction of movement of the Fabric the improvement comprising said means for sewing two seams including two pairs of needles mounted on said first arm for reciprocating movement towards and away from said second arm, one pair of needles being offset from the other in the direction of said seams with a first needle of each of said two pairs of needles being positioned in approximate alignment, in the direction of said seams, with said means for slitting the fabric between said two seams so that said first needle of each pair will enter the slit in the fabric, two pairs of hooks, a first pair being carried on said first arm and a second pair being carried on said second arm, means for feeding threads to said two pairs of needles and said two pairs of hooks and means for imparting synchronised sewing movements to said needles and said hooks whereby to form in a single operation two double rows of stitches and to slit the fabric tubes between the two double rows of stitches to form a pair of tights from said two fabric tubes.
 2. The sewing machine of claim 1, wherein said arms are of a length at least equal to the length of a seam from the crutch portion to the waist of a pair of tights.
 3. The sewing machine of claim 1, wherein said first arm is the upper arm and it carries said means for slitting the fabric being sewn, said two pairs of needles and an upper pair of said two pairs of hooks and said second arm is the lower arm and it carries a lower pair of said two pairs of hooks.
 4. The sewing machine of claim 3, wherein each pair of said two pairs of needles operates in combination with an associated lower hook to form a double row of stitches comprising two threads which pass through the fabric and form loops on the lower side thereof, which loops are interlaced with loops of a covering thread on the lower side of said fabric, which extends transversely between the loops of said two threads of the associated double row of stitches.
 5. The sewing machine of claim 4, wherein each pair of said needles also cooperates with an associated one of said upper hooks to interlace the loops of said two threads which pass through said fabric with a filling cord on the upper side of said fabric. 